The purpose of this research study is to examine the effect of cardiac sympathetic denervation (CSD) surgery on life threatening abnormal heart rhythms called ventricular tachycardia or ventricular fibrillation that can lead to sudden cardiac death. Subjects will be asked to participate in this research study if they have recurrent ventricular tachycardia (at least one ICD shock for ventricular tachycardia) and have undergone at least one catheter ablation procedure or have ventricular tachycardia or fibrillation that is not ablatable. The goal of this study is to determine whether cardiac sympathetic denervation can prevent these abnormal heart rhythms from occurring and therefore, prevent, ICD shocks which are not only painful, but have been shown to reduce quality of life and/or lead to depression, particularly in the period immediately after the shock.